Bad cough besets king who complains (6)
I believe the answer is:
grouch
'bad cough besets king who complains' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'bad cough besets king' is the wordplay.
'bad' indicates an anagram.
'besets' indicates putting letters inside (beset can mean to surround).
'king' becomes 'R' (abbreviation for rex, king in Latin).
'cough' anagrammed gives 'gouch'.
'gouch' going around 'r' is 'GROUCH'.
Can you help me to learn more?
(Other definitions for grouch that I've seen before include "One miserable" , "Person continually grumbling" , "'Crosspatch, grump (6)'" , "Bad-tempered complainant" , "Grumble - complain" .)